Basic Use Of Classes - Help

This is a discussion on Basic Use Of Classes - Help within the C++ Programming forums, part of the General Programming Boards category; I seem to be getting this error:
Converter.obj : error LNK2019: unresolved external symbol "public: double __thiscall convert::MPH2KM(double)" (?MPH2KM@convert@@QAENN@Z) referenced ...

1) They are meant to represent real world objects with properties (car; bank account; etc.) rather than actions (convert; jump; etc.). So creating a class called "Convert" is kinda weird where simple functions in your main file would make more sense.

2) Also, the header ".h" and implementation file ".cpp" naming convention tends to be the same as the enclosed class. (i.e. convert.h & convert.cpp).

I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.

1) They are meant to represent real world objects with properties (car; bank account; etc.) rather than actions (convert; jump; etc.). So creating a class called "Convert" is kinda weird where simple functions in your main file would make more sense.

If that is meant to be a general rule of thumb, then I would disagree somewhat. classes can also represent functors (classes which overload operator() ), objects of these classes can be used in a manner very similar to functions, in which case, it would make alot of sense to name the class to reflect an ability or method.

just to go back on topic, here's one way the OP's program could have been written with functors

I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.